Programa de Pós-Graduação em Genética e Biologia Molecular, Departamento de Genética, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.
Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.
Mob DNA. 2012 Aug 31;3(1):13. doi: 10.1186/1759-8753-3-13.
Miniature inverted-repeat transposable elements (MITEs) are short, nonautonomous DNA elements flanked by subterminal or terminal inverted repeats (TIRs) with no coding capacity. MITEs were originally recognized as important components of plant genomes, where they can attain extremely high copy numbers, and are also found in several animal genomes, including mosquitoes, fish and humans. So far, few MITEs have been described in Drosophila.
Herein we describe the distribution and evolution of Mar, a MITE family of hAT transposons, in Drosophilidae species. In silico searches and PCR screening showed that Mar distribution is restricted to the willistoni subgroup of the Drosophila species, and a phylogenetic analysis of Mar indicates that this element may have originated prior to the diversification of these species. Most of the Mar copies in D. willistoni present conserved target site duplications and TIRs, indicating recent mobilization of these sequences. We also identified relic copies of potentially full-length Mar transposon in D. tropicalis and D. willistoni. The phylogenetic relationship among transposases from the putative full-length Mar and other hAT superfamily elements revealed that Mar is placed into the recently determined Buster group of hAT transposons.
On the basis of the obtained data, we can suggest that the origin of these Mar MITEs occurred before the subgroup willistoni speciation, which started about 5.7 Mya. The Mar relic transposase existence indicates that these MITEs originated by internal deletions and suggests that the full-length transposon was recently functional in D. willistoni, promoting Mar MITEs mobilization.
微型反向重复转座元件（MITEs）是短的、非自主的 DNA 元件，两侧为亚末端或末端反向重复（TIRs），没有编码能力。MITEs 最初被认为是植物基因组的重要组成部分，在植物基因组中，它们可以达到极高的拷贝数，也存在于包括蚊子、鱼类和人类在内的几种动物基因组中。到目前为止，在果蝇中描述的 MITE 很少。
本文描述了 Mar，一种 hAT 转座子的 MITE 家族，在果蝇科物种中的分布和进化。计算机搜索和 PCR 筛选表明，Mar 的分布仅限于果蝇种的 willistoni 亚组，Mar 的系统发育分析表明，该元件可能起源于这些物种的多样化之前。在 D. willistoni 中，大多数 Mar 拷贝都存在保守的靶位点重复和 TIRs，表明这些序列最近发生了移动。我们还在 D. tropicalis 和 D. willistoni 中鉴定到潜在全长 Mar 转座子的遗迹拷贝。来自假定全长 Mar 和其他 hAT 超家族元件的转座酶的系统发育关系表明，Mar 被置于最近确定的 Buster 组 hAT 转座子中。
根据获得的数据，我们可以推测这些 Mar MITEs 的起源发生在 willistoni 亚组分化之前，大约在 570 万年前。Mar 遗迹转座酶的存在表明这些 MITEs 是通过内部缺失产生的，并表明全长转座子在 D. willistoni 中最近是功能性的，促进了 Mar MITEs 的移动。
